types/variant.c

   1 /*
   2  * variant.c
   3  *
   4  * BabelTrace - Variant Type Converter
   5  *
   6  * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  */
  18
  19 #include <babeltrace/compiler.h>
  20 #include <babeltrace/format.h>
  21 #include <errno.h>
  22
  23 static
  24 struct definition *_variant_definition_new(struct declaration *declaration,
  25                                 struct definition_scope *parent_scope,
  26                                 GQuark field_name, int index);
  27 static
  28 void _variant_definition_free(struct definition *definition);
  29
  30 void variant_copy(struct stream_pos *dest, const struct format *fdest,
  31                   struct stream_pos *src, const struct format *fsrc,
  32                   struct definition *definition)
  33 {
  34         struct definition_variant *variant =
  35                 container_of(definition, struct definition_variant, p);
  36         struct declaration_variant *variant_declaration = variant->declaration;
  37         struct field *field;
  38         struct declaration *field_declaration;
  39
  40         fsrc->variant_begin(src, variant_declaration);
  41         if (fdest)
  42                 fdest->variant_begin(dest, variant_declaration);
  43
  44         field = variant_get_current_field(variant);
  45         field_declaration = field->definition->declaration;
  46         field_declaration->copy(dest, fdest, src, fsrc, field->definition);
  47
  48         fsrc->variant_end(src, variant_declaration);
  49         if (fdest)
  50                 fdest->variant_end(dest, variant_declaration);
  51 }
  52
  53 static
  54 void _untagged_variant_declaration_free(struct declaration *declaration)
  55 {
  56         struct declaration_untagged_variant *untagged_variant_declaration =
  57                 container_of(declaration, struct declaration_untagged_variant, p);
  58         unsigned long i;
  59
  60         free_declaration_scope(untagged_variant_declaration->scope);
  61         g_hash_table_destroy(untagged_variant_declaration->fields_by_tag);
  62
  63         for (i = 0; i < untagged_variant_declaration->fields->len; i++) {
  64                 struct declaration_field *declaration_field =
  65                         &g_array_index(untagged_variant_declaration->fields,
  66                                        struct declaration_field, i);
  67                 declaration_unref(declaration_field->declaration);
  68         }
  69         g_array_free(untagged_variant_declaration->fields, true);
  70         g_free(untagged_variant_declaration);
  71 }
  72
  73 struct declaration_untagged_variant *untagged_variant_declaration_new(
  74                                       struct declaration_scope *parent_scope)
  75 {
  76         struct declaration_untagged_variant *untagged_variant_declaration;
  77         struct declaration *declaration;
  78
  79         untagged_variant_declaration = g_new(struct declaration_untagged_variant, 1);
  80         declaration = &untagged_variant_declaration->p;
  81         untagged_variant_declaration->fields_by_tag = g_hash_table_new(g_direct_hash,
  82                                                        g_direct_equal);
  83         untagged_variant_declaration->fields = g_array_sized_new(FALSE, TRUE,
  84                                                  sizeof(struct declaration_field),
  85                                                  DEFAULT_NR_STRUCT_FIELDS);
  86         untagged_variant_declaration->scope = new_declaration_scope(parent_scope);
  87         declaration->id = CTF_TYPE_UNTAGGED_VARIANT;
  88         declaration->alignment = 1;
  89         declaration->copy = NULL;
  90         declaration->declaration_free = _untagged_variant_declaration_free;
  91         declaration->definition_new = NULL;
  92         declaration->definition_free = NULL;
  93         declaration->ref = 1;
  94         return untagged_variant_declaration;
  95 }
  96
  97 static
  98 void _variant_declaration_free(struct declaration *declaration)
  99 {
 100         struct declaration_variant *variant_declaration =
 101                 container_of(declaration, struct declaration_variant, p);
 102
 103         _untagged_variant_declaration_free(&variant_declaration->untagged_variant->p);
 104         g_array_free(variant_declaration->tag_name, TRUE);
 105 }
 106
 107 struct declaration_variant *
 108         variant_declaration_new(struct declaration_untagged_variant *untagged_variant, const char *tag)
 109 {
 110         struct declaration_variant *variant_declaration;
 111         struct declaration *declaration;
 112
 113         variant_declaration = g_new(struct declaration_variant, 1);
 114         declaration = &variant_declaration->p;
 115         variant_declaration->untagged_variant = untagged_variant;
 116         variant_declaration->tag_name = g_array_new(FALSE, TRUE, sizeof(GQuark));
 117         append_scope_path(tag, variant_declaration->tag_name);
 118         declaration->id = CTF_TYPE_VARIANT;
 119         declaration->alignment = 1;
 120         declaration->copy = variant_copy;
 121         declaration->declaration_free = _variant_declaration_free;
 122         declaration->definition_new = _variant_definition_new;
 123         declaration->definition_free = _variant_definition_free;
 124         declaration->ref = 1;
 125         return variant_declaration;
 126 }
 127
 128 /*
 129  * tag_instance is assumed to be an enumeration.
 130  * Returns 0 if OK, < 0 if error.
 131  */
 132 static
 133 int check_enum_tag(struct definition_variant *variant,
 134                    struct definition *enum_tag)
 135 {
 136         struct definition_enum *_enum =
 137                 container_of(enum_tag, struct definition_enum, p);
 138         struct declaration_enum *enum_declaration = _enum->declaration;
 139         int missing_field = 0;
 140         unsigned long i;
 141
 142         /*
 143          * Strictly speaking, each enumerator must map to a field of the
 144          * variant. However, we are even stricter here by requiring that each
 145          * variant choice map to an enumerator too. We then validate that the
 146          * number of enumerators equals the number of variant choices.
 147          */
 148         if (variant->declaration->untagged_variant->fields->len != enum_get_nr_enumerators(enum_declaration))
 149                 return -EPERM;
 150
 151         for (i = 0; i < variant->declaration->untagged_variant->fields->len; i++) {
 152                 struct declaration_field *field_declaration =
 153                         &g_array_index(variant->declaration->untagged_variant->fields,
 154                                        struct declaration_field, i);
 155                 if (!enum_quark_to_range_set(enum_declaration, field_declaration->name)) {
 156                         missing_field = 1;
 157                         break;
 158                 }
 159         }
 160         if (missing_field)
 161                 return -EPERM;
 162
 163         /*
 164          * Check the enumeration: it must map each value to one and only one
 165          * enumerator tag.
 166          * TODO: we should also check that each range map to one and only one
 167          * tag. For the moment, we will simply check this dynamically in
 168          * variant_declaration_get_current_field().
 169          */
 170         return 0;
 171 }
 172
 173
 174
 175 static
 176 struct definition *
 177         _variant_definition_new(struct declaration *declaration,
 178                                 struct definition_scope *parent_scope,
 179                                 GQuark field_name, int index)
 180 {
 181         struct declaration_variant *variant_declaration =
 182                 container_of(declaration, struct declaration_variant, p);
 183         struct definition_variant *variant;
 184         unsigned long i;
 185
 186         variant = g_new(struct definition_variant, 1);
 187         declaration_ref(&variant_declaration->p);
 188         variant->p.declaration = declaration;
 189         variant->declaration = variant_declaration;
 190         variant->p.ref = 1;
 191         variant->p.index = index;
 192         variant->scope = new_definition_scope(parent_scope, field_name);
 193         variant->enum_tag = lookup_definition(variant->scope->scope_path,
 194                                               variant_declaration->tag_name,
 195                                               parent_scope);
 196
 197         if (!variant->enum_tag
 198             || check_enum_tag(variant, variant->enum_tag) < 0)
 199                 goto error;
 200         definition_ref(variant->enum_tag);
 201         variant->fields = g_array_sized_new(FALSE, TRUE,
 202                                             sizeof(struct field),
 203                                             variant_declaration->untagged_variant->fields->len);
 204         g_array_set_size(variant->fields, variant_declaration->untagged_variant->fields->len);
 205         for (i = 0; i < variant_declaration->untagged_variant->fields->len; i++) {
 206                 struct declaration_field *declaration_field =
 207                         &g_array_index(variant_declaration->untagged_variant->fields,
 208                                        struct declaration_field, i);
 209                 struct field *field = &g_array_index(variant->fields,
 210                                                      struct field, i);
 211
 212                 field->name = declaration_field->name;
 213                 /*
 214                  * All child definition are at index 0, because they are
 215                  * various choices of the same field.
 216                  */
 217                 field->definition =
 218                         declaration_field->declaration->definition_new(declaration_field->declaration,
 219                                                           variant->scope,
 220                                                           field->name, 0);
 221         }
 222         variant->current_field = NULL;
 223         return &variant->p;
 224 error:
 225         free_definition_scope(variant->scope);
 226         declaration_unref(&variant_declaration->p);
 227         g_free(variant);
 228         return NULL;
 229 }
 230
 231 static
 232 void _variant_definition_free(struct definition *definition)
 233 {
 234         struct definition_variant *variant =
 235                 container_of(definition, struct definition_variant, p);
 236         unsigned long i;
 237
 238         assert(variant->fields->len == variant->declaration->untagged_variant->fields->len);
 239         for (i = 0; i < variant->fields->len; i++) {
 240                 struct field *field = &g_array_index(variant->fields,
 241                                                      struct field, i);
 242                 definition_unref(field->definition);
 243         }
 244         definition_unref(variant->enum_tag);
 245         free_definition_scope(variant->scope);
 246         declaration_unref(variant->p.declaration);
 247         g_free(variant);
 248 }
 249
 250 void untagged_variant_declaration_add_field(struct declaration_untagged_variant *untagged_variant_declaration,
 251                             const char *field_name,
 252                             struct declaration *field_declaration)
 253 {
 254         struct declaration_field *field;
 255         unsigned long index;
 256
 257         g_array_set_size(untagged_variant_declaration->fields, untagged_variant_declaration->fields->len + 1);
 258         index = untagged_variant_declaration->fields->len - 1;  /* last field (new) */
 259         field = &g_array_index(untagged_variant_declaration->fields, struct declaration_field, index);
 260         field->name = g_quark_from_string(field_name);
 261         declaration_ref(field_declaration);
 262         field->declaration = field_declaration;
 263         /* Keep index in hash rather than pointer, because array can relocate */
 264         g_hash_table_insert(untagged_variant_declaration->fields_by_tag,
 265                             (gpointer) (unsigned long) field->name,
 266                             (gpointer) index);
 267         /*
 268          * Alignment of variant is based on the alignment of its currently
 269          * selected choice, so we leave variant alignment as-is (statically
 270          * speaking).
 271          */
 272 }
 273
 274 struct declaration_field *
 275 untagged_variant_declaration_get_field_from_tag(struct declaration_untagged_variant *untagged_variant_declaration, GQuark tag)
 276 {
 277         unsigned long index;
 278
 279         index = (unsigned long) g_hash_table_lookup(untagged_variant_declaration->fields_by_tag,
 280                                                     (gconstpointer) (unsigned long) tag);
 281         return &g_array_index(untagged_variant_declaration->fields, struct declaration_field, index);
 282 }
 283
 284 /*
 285  * field returned only valid as long as the field structure is not appended to.
 286  */
 287 struct field *variant_get_current_field(struct definition_variant *variant)
 288 {
 289         struct definition_enum *_enum =
 290                 container_of(variant->enum_tag, struct definition_enum, p);
 291         struct declaration_variant *variant_declaration = variant->declaration;
 292         unsigned long index;
 293         GArray *tag_array;
 294         GQuark tag;
 295
 296         tag_array = _enum->value;
 297         /*
 298          * The 1 to 1 mapping from enumeration to value should have been already
 299          * checked. (see TODO above)
 300          */
 301         assert(tag_array->len == 1);
 302         tag = g_array_index(tag_array, GQuark, 0);
 303         index = (unsigned long) g_hash_table_lookup(variant_declaration->untagged_variant->fields_by_tag,
 304                                                     (gconstpointer) (unsigned long) tag);
 305         variant->current_field = &g_array_index(variant->fields, struct field, index);
 306         return variant->current_field;
 307 }